“For decades, Mr Rhodes, it is clear you have wanted the democracy of this country to devolve into violence,” US District Judge Amit Mehta said.

“You are not a political prisoner, Mr Rhodes,” he said, adding that he believes Rhodes represents an “ongoing threat” to the country.

Rhodes, a former army paratrooper turned Yale-educated lawyer, was convicted in November by a federal court jury in Washington DC.

Mehta also on Thursday sentenced co-defendant Kelly Meggs, a former Florida Chapter leader also convicted of seditious conspiracy, to 12 years in prison.

Prosecutors asked Mehta to sentence Meggs, the group’s former Florida chapter leader, to 21 years in prison, although Meggs’ family members urged the judge to look at the defendant’s good qualities as a protector and provider in his role as a father, brother and husband.

Meggs’ wife Connie was also separately convicted in a different trial with other associates of the Oath Keepers for their roles in the Capitol attack.

Meggs admitted that he should have never entered the Capitol grounds but he nevertheless denied that he planned his actions in advance, and he blamed his “vile and hateful language” for leading to his conviction.

Rhodes’ prison term represents the longest sentence for any of the more than 1000 people charged in connection with the January 6, 2021, Capitol attack by supporters of Republican then-president Donald Trump in a failed bid to block Congress from certifying Democratic rival Joe Biden’s November 2020 election victory.

Until now, the longest sentence was 14 years in prison given to a Pennsylvania man who attacked police during the rampage.

Prosecutors had sought a sentence of 25 years for Rhodes.

“Mr Rhodes led a conspiracy to use force and violence to intimidate and coerce members of our government into stopping the lawful transfer of power following a presidential election,” federal prosecutor Kathryn Rakoczy said.

“As the court has just found – that is terrorism.”

Ahead of his sentencing, a defiant Rhodes stood before Mehta, clad in an orange jumpsuit, and insisted that he is a “political prisoner” who, like Trump, was trying to oppose people “who are destroying our country”.

“I believe this country is incredibly divided. And this prosecution – not just of me, but of all J6ers – is making it even worse. I consider every J6er a political prisoner and all of them are being grossly overcharged,” he said.

He also vowed to “to expose the criminality of this regime” from his prison cell.

In addition to seditious conspiracy – a felony charge involving attempting “to overthrow, put down or to destroy by force the government of the United States” – Rhodes was convicted of obstructing an official proceeding and tampering with documents.

Rhodes was acquitted of two other charges.

As part of their sentencing request, prosecutors asked the judge to enhance Rhodes’ sentence based on several factors, including his “terroristic conduct”.

Mehta agreed that all of those proposed sentencing enhancements could be applied, saying the evidence showed that Rhodes “was at the top of the chain” and he was culpable for the actions of the entire group.

Rhodes, who wears an eye patch after accidentally shooting himself in the face with his own gun, founded the Oath Keepers in 2009.

The militia group’s members include current and retired US military personnel, law enforcement officers and first responders.

Some of the Oath Keepers breached the Capitol clad in paramilitary gear.

Others at a suburban hotel staged a “quick reaction force” prosecutors said was equipped with firearms that could be quickly transported into Washington DC.

Rhodes was on Capitol grounds that day but did not enter the building.

-AAP